The present inventive concept herein relates to liquid crystal display device, and more particularly, to a liquid crystal display device using a blue phase liquid.
Polymer-stabilized blue phase liquid crystal displays (PS-BPLCD) have attracted much interest as promising next-generation liquid crystal displays due to the advantages that it can align the liquid crystal without an alignment layer and can get a driving speed 100 times higher than that of a conventional nematic liquid crystal display. However, a conventional PS-BPLCD has not been yet commercialized because of a high driving voltage and a low optical transmittance. In the conventional PS-BPLCD, a driving characteristic is obtained by an in-phase switching (IPS) method because the amount of birefringence having an optical axis in an electric filed direction increases as a voltage applied increases. When performing the IPS method, since an upper portion of patterned electrode cannot obtain a transmitted light effectively, it is forced to have a characteristic of low aperture ratio and since a strength of horizontal electric field is rapidly reduced near the top substrate in which an electrode is not formed, the amount of induced birefringence is very small. Those are root causes making the conventional PS-BPLCD have a low transmittance and a high driving voltage together with the reduction of effective electric field caused by a polymer doped to get a stabilized blue phase in a wide temperature range.
When driving the PS-BPLCD using a vertical electric field, since an optical axis is formed in parallel to a progress direction of vertically entered light, a gray-scale property according to a voltage cannot be obtained between crossed polarizers.